Fluid-actuated timer



` June 24, 19,69 w. E. BuFoRn `ET A1. 3,451,414

FLUID-ACTUATED TIMER Filed nec. 23, 196e 4 sheet or a 92 9;; nai/252620 I8 la, 9

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June 24, Y1969 FLUID-ACTUATED TIMER sheeting Filed Dec. 23, 1966 Wsuf y E', .B UFoRD CHQQL es G, .B Uffa/2P INVENTORS United States Patent O 3,451,414 FLUID-ACTUATED TIMER ABSTRACT F THE DISCLOSURE A pneumatically actuated timer having a housing containing two chambers separated by a valve element and a diaphragm adjacent the valve element, and adapted upon admission of compressed air to the device to first admit the air into one of the chambers in a relation actuating the valve element to a first position, and to subsequently admit air from the sour-ce into the other chamber past a restriction, in a manner causing `a predetermined delay interval before the pressure in the second chamber can reach a sufficient value to actuate the valve, by virtue of a differential area relationship, to a second position, .in which the Ivalve passes air as a timed signal to a mechanism being controlled.

This invention relates to improved timer devices for accurately timing a predetermined interval, as for the purpose of controlling the timed operation of yan automatic mechanism. The invention is particularly concerned with timers which are actuated and controlled by the energy of a pressurized fluid, such as air.

Though there have in the past been devised numerous different types of fluid actuated timing units, none of these with which we lare familiar has been capable of the precision and accuracy which is required for many timing operations. As a result, it has been necessary, in many instances in which fluid operated timers would otherwise be desirable, to substitute electrical or electronic timers in order to `assure accuracy, even though such electrically operated units may often introduce a danger of re, explosion, electrocution, or other similar difficulties. Besides these safety hazards, fluid actuated timers would in many instances be preferable (if 4sufficiently accurate) because in controlling some types of apparatus compressed air or other pressurized fluid is more readily available than is the electrical energy required for an electric timer.

A major object of the present invention is to provide a fluid actuated timer which has extreme accuracy, and which can retain that accuracy over long -periods of time and under changing environmental conditions. In particular, it has been found that timers embodying the invention are capable of very effectively timing intervals to a tolerance as small as one one-hundredth of a second, even though the overall period timed may be relatively extended. The unit may be designed to eliminate any substantial variance in the timed interval as a result of `wear of any of the parts, expansion or contraction o-f springs or other elements upon a change in temperature or the like, or variations in any of the other critical factors which have in prior devices introduced uncontrollable and unpredictable errors into the timing intervals. In addition to this extreme accuracy, a unit embody- 3,451,414 Patented June 24, 1969 ing the invention may also be structurally very simple and inexpensive to manufacture, and be `very small in size.

A further object of the invention is to provide a timer of the above discussed type in which the timed interval can be controllably varied within a relatively wide range, to enable timing by the device of intervals of different lengths. However, in spite of this capacity for wide adjustment of the time period involved, the device is capable ofbe'ing set very precisely to any desired interval within that range, and for this purpose preferably has two different types of interval adjustments, one being a coarse adjustment and the other a fine or precise adjustment.

Structurally, a device embodying the invention includes means forming a chamber to which there is fluid communication through a restricted passage, in a manner such that the relatively slow leakage of fluid through that passage acts to determine when the desired time has elapsed. Preferably, two chambers are provided for receiving pressure fluid, with the fluid in these chambers acting to urge a controlled element in opposite directions. The compressed air or other fluid is fed into one of these chambers in a sufficiently restricted manner to require a predetermined interval before pressure in that chamber can build up to a point at which it displaces the controlled element. Adjustment of the time interval may be accomplished by variation of the effective chamber size, and by variation of the size of the restriction to fluid ilow into one of the chambers.

The controlled element is desirably a valve, which is actuable between open and closed positions upon the attainment of the full actuating pressure within the chamber into which fluid flows in restricted fashion. A diaphragm may be provided for exerting force against the movable valve element, which diaphragm may also serve to control the opening and closing of a vent passage leading to atmosphere from the valve compartment.

Certain additional features of the invention relate to the provision of a fluid exhaust valve arrangement for ultimately discharging the accumulated pressure fluid from the chamber into `which the fluid is filled in restricted manner, and also relate to various other highly effective structural features of the apparatus.

The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawings, in which:

FIG. l is a perspective view of a timer embodying the invention;

FIG. 1a is an enlarged horizontal section taken on line la-la of FIG. 1;

FIGS. 2, 3, and 4 are transverse sections taken on lines 2--2, 33, and 4-4 respectively of FIG. 1;

FIG. S is a section taken on line 5 5 of FIG. 4;

FIG. 6 is a fragmenary section taken on line 6--6 of FIG. 5;

FIG. 7 is a view corresponding to a portion of FIG. 1, but showing the valve in open position; and

FIG. 8 shows an arrangement in which an auxiliary chamber has been connected to the timer to vary the timed interval.

Referring first to FIGS. 1 and 1a, we have illustrated at 10 a timer device constructed in accordance with the invention, and which will be discussed as adapted for actuation by compressed air, though it is contemplated that other pressurized fluids may in some instances be utilized.

The compressed air is fed to timer from a source 11 of such pressurized air, through a line 12 into which there is connected a valve 13 which may typically be adapted to admit compressed air to the timer upon manual actuation of an operating element 14. The purpose of the timer is to admit a charge of pressurized air to a controlled unit 15 upon the expiration of a predetermined timed interval following opening of air valve 13. Unit 15 may for example be an air operated switch, piston and cylinder mechanism, diaphragm, or any other unit to be controlled.

Timer 10 includes a rigid body 16, typically formed of an appropriate metal, plastic, or other suitable material, and which may include a main body part 17 and a cover 18 suitably secured to part 17 as by screws 19. Body 16 is hollow to contain two chambers 20 and 21 which are separated from one another by a flexible circular diaphragm 22 and a valve element 23.

Chamber is dened primarily by the internal configuration of cover 18, forming a cylindrical side wall 24 of the chamber disposed about main axis 25 of the device, and with the cover forming a transverse end wall 26 of the chamber disposed perpendicular to axis 25. At the center of end wall 26, cover 18 may form a cylindrical boss or projection 126 containing a central axial bore 27 within which a valve guiding pin 28 is partially received in fixed press fit relation. Pin 28 is formed of a hardened steel or other metal, and projects along axis 25 into a bore or passage 29 formed in valve element 23, with the pin being a close sliding llt in this bore to effectively guide the valve element for only axial movement relative to body 16, and to center the valve element and retain it against any substantial lateral movement from a properly located position. A light compression spring 30 is received between the end of projection 126 and valve element 23, and lightly urges the valve element to its FIG. l closed position.

The second air chamber 21 is formed primarily by the main body part 17, which has an internal cylindrical surface 31 centered about axis 25 and desirably of a diameter greater than the diameter of side wall surface 24 of chamber 20. The effective size of chamber 21 is rendered controllably adjustable by provision of a piston like movable end wall 32 of the chamber, which wall may take the form essentially of a rigid circular disc disposed transversely of axis 25, and having a deformable seal ring or O-ring 33 contained in a peripheral groove in wall 32 and engageable annularly in sealing relation with side wall surface 31 of chamber 21. At its center, the piston or wall 32 may be rigidly connected in iluid tight sealed relation to the end 34 of an actuating screw 35, which projects outwardly through transverse end wall 36 of main body part 17, and engages internal threads 37 formed in a nut element 38. Element 38 rigidly carries a typically externally knurled adjusting knob 39 at the outside of the body, with the rigid connection between these two parts being illustrated as formed by tightening of a set screw represented at 40. As will be apparent, the externally cylindrical surface 41 of nut element 38 is rotatable within a cylindrical bore or passageway v42 formed in the end wall 36 of the body, while the assembly 38-39 is retained against axial movement by engagement of an annular flange 43 on element 38 and an annular shoulder 44 on element 39 with opposite sides of the housing wall 36. Thus, rotation of knob 39 at the outside of the housing acts to adjustably shift the piston or wall 32 axially within the body, between the two extreme positions illustrated in broken lines at 32 and 32", to correspondingly vary the effective size of chamber 21 from a very small minimum size to a relatively large maximum size.

Adjacent diaphragm 22, body part 17 may have a short cylindrical surface 45 of a diameter slightly larger than and concentric with surface 31, and beyond which body 17 forms a transverse annular shoulder surface 46 which is centered about and perpendicular to axis 25. Beyond shoulder 46, body 17 has an internal surface 47 of a diameter greater than either of the surfaces 31 and 45, and which surface 47 is continuous from shoulder 46 to an annular transverse cover engaging end face 48, except insofar as surface 47 is interrupted by two annular air conducting grooves 49 and 50, and an intermediate groove containing an annular deformable seal ring 51.

About valve element 23, body part 17 contains an annular rigid valve seat and fluid conducting member 52, which has an outer cylindrical surface 53 of a diameter fitting closely within surface 47 of the body, and annularly contacting O-ring 51 in fluid tight sealing relation. At one of its ends, member 52 has a transverse annular surface 54 which engages the periphery of circular diaphragm 22 in a relation clamping that diaphragm annularly against shoulder 46 of the body part. At its opposite end, member 52 has a transverse annular end surface 55 engaging a correspondingly transverse annular surface 56 of cover 18, with member 52 being sufficiently thick axially to be clamped tightly against diaphragm 22 by tightening of the cover screws 19. An O-ring 57 forms an annular fluid tight seal between member 52 and each of the body parts 17 and 18.

Internally (see FIG. 7), member 52 has a short cylindrical surface 158 forming a continutaion of side wall 24 of chamber 20, and meeting a transverse annular inwardly extending surface 58 forming a seat for valve element 23. At the inner extremity of surface 58, a member 52 has a reduced diameter internal axially extending cylindrical surface 59, which at its opposite end meets a transverse annular surface 60 extending outwardly to a cylindrical surface 61 which may be of a diameter corresponding to the previously mentioned surface 158. About surface 61, member 52 contains an axially facing annular groove 62, which communicates through two or more radially extending passages 63 in member 52 with groove 50 in the wall of body part 17. Diaphragm 22 is capable of closing off communication between groove 62 and the space radially inwardly of surface 61 by annular contact of the diaphragm with member 52 at the location designated 64 along the radially inner side of the groove. The diaphragm 22 may be formed of any appropriate flexible and desirably resilient fluid impervious material such as a suitable neoprene rubber. This diaphragm normally extends substantially directly transversely of axis 25, except to the extent that the diaphragm may be distorted by valve element 23 or by air pressure in the device.

Air passage 50 in body part 17 communicates with the atmosphere through a vent passage 66 extending through the side wall of body part 17. A very restricted communication between groove 62 and the space radially inwardly of surface 61 of member 52 is provided through a very small dimension passage 67 formed in the inner side wall of the groove (see FIG. 7).

Valve element 23 may for purposes of assembly be formed of two parts 68 and y69, meeting annularly at 70, and secured rigidly together by a screw 71. Part 69 may have a cylindrical axially projecting portion 72 which is a close fit within cylindrical passage 73 in part 68 and is sealed annularly with respect thereto by O-rings 74.

Together, these two valve parts 68 and 69 form the valve assembly or element 23 having a transverse circular surface 75 facing chamber 20, and a transverse circular surface 76 facing chamber 21 and engageable with diaphragm 22. Externally, the valve element or assembly 23 forms two circularly spaced annular radially outwardly projecting flanges 77 and 78, with a reduced diameter externally cylindrical surface 79 extending axially therebetween. Flange '77 is of an external diameter less than flange 78, to introduce a differential in response to the pressures within the two chambers 20 and 21. Flange 77 has an outer cylindrical surface 80 and a transverse annular surface 81 to which there is bonded an annular ridge or bead 82 of deformable material, such as a suitable neoprene rubber, which is annularly engageable `in valving relation with surface 58 of member 52. The second flange 78 is defined by an outer cylindrical surface 83 and a transverse annular surface 84. As will be apparent from FIG. 1a, the outer surfaces of valve element or assembly 23 are spaced slightly at all points from the internal surfaces of member 52, to prevent the development of friction between these parts, and to allow flow of air between the parts at all points. The axial spacing between tlange 78 of the valve element and surface 60 of member 52 enables the valve element :to -be moved upwardly slightly to its FIG. 7 position, in which air may liow from chamber past valve bead or ridge 82 and ultimately into a radial passage or passages 85 extending through member 52 and communicating with groove 49 in the body wall. This groove 49 in turn communicates through an outlet opening 90 in the body wall with a line 91 leading to the previously discussed unit 15 which is to be controlled in timed fashion by timer 10.

Actuating air is admitted into the body 16 from valve 13 through an inlet Ipassage 92 (FIGS. la and 5), which leads through a very restricted passageway 93 into chamber 20. The inlet passage 92 also communicates in less restricted fashion with a ball valve chamber 94 (FIG. 5), through a relatively large dimension passage 95 formed in the body at a level beneath the plane of FIG. 5, and a communicating transverse passage 106. One end of this ball valve chamber 94 may be closed and sealed by a threaded plug 96, while the opposite end contains a lluid actuated ball valve element 97 adapted to engage an annular valve seat 98 formed in body part 17, in a manner closing off communication between a passage 99 and an air exhaust passage 100. The passage 99 communicates with the interior of chamber 21 through a passage 101 which extends within body part 17 essenu tially transversely of axis 25, and is essentially tangent with respect to side wall surface of chamber 21 (FIGS. la and 4), and opens into chamber 21 through an opening 102. The opposite end of passage 101 communicates with an external opening 103, which may normally be closed by a plug 104.

Air is admitted linto chamber 21 past a minutely adjustable metering valve 105, to which air from inlet 92 and passage 95 is delivered through transverse passage 106 (FIG. 5). This metering valve admits compressed air in restricted fashion into a passage 107 leading lto the previously mentioned passage 101 which communicates at 102 with chamber 21.

Metering valve 105 is illustrated as including a cylindrical tubular body 108, which is held in position within body :part 17 by a part 109 threadedly engaging part 17 at 110 (and containing a notch 210 through which air may flow from passage 106 past part 17). A valve element proper 111 is movable axially into and out of cylindrical passage 112 in element 108, to vary the restriction to air flow offered by assembly 105. Element 111 may be urged in an opening direction by a coil spring 113 engaging an outer flange 114 of element 111. A screw 115 adjustably actuates element 11 axially inwardly, and is manually operated by a knob 116 at the outside of the body. As will be apparent from FIGS. 5 and 6, the valve element 111 is desirably of a type having an external cylindrical surface 117 Which`is a close sliding fit within passage 112 in element 108, but which is interrupted at one side of element 111 to form a flat surface 118 in a manner leaving a restricted fluid passage at 119` be tween that flat and the wall of passage 112. This flat is disposed at a gradual tapering angle with respect to the axis of passage 112 (FIG. 5), so that the size of the restricted passage 119 at its entrance end is adjusted minutely and progressively in accordance with the axial position of valve element 111. If desired, a conventional needle valve or other valve element may be substituted for the metering valve 105, but the illustrated arrangement is preferred because of its capacity to meter the 6 air very precisely without danger of jamming of the valve element in its body. In any event, the restriction to air flow offered by valve 105 should be much greater than the restriction offered at 93 to flow of air into chamber 20, so that the pressure in chamber 20 always builds up much more rapidly than in chamber 21.

To describe now a cycle of operation of the timer, assume iirst of all that the air supply valve 14 is closed, and 4that valve element 23 is held lightly `by spring 30 in its FIG. la position in which the valving ridge 82 is in contact with seat surface 58. When an operator then opens valve 14 to admit air to timer 10, the timer commences a cycle of operation resulting in delivery of air to the timed unit 15 after the expiration of a predetermined accurately timed delay interval. Upon opening of valve 14, air flows through passages 92 and 93 into chamber 20, to build up the pressure in that chamber in a manner coacting with spring 30 in holding the valve in its FIG. 1 closed position. Also, opening of valve 14 admits air through passage to chamber 94 (FIG. 5), to urge valve element 97 into contact with annular seat surface 98, in a manner preventing escape of any air from chamber 21 to the atmosphere. Further, the opening of valve 14 commences the ow of air through metering valve and passages 107 and 101 into chamber 21, to thereby very gradually increase the pressure within chamber 21 (more gradually than in chamber 20) at a rate determined precisely by the predetermined setting of valve element 111. Immediately upon commencement of the slightest increase in pressure within chamber 21, diaphragm 22 is urged upwardly to a position in which its peripheral portion contacts member 52 annularly at 64 (FIG. 7), to close off almost all communication (except through small vent passage 67) to the atmosphere from the space radially between valve element 23 and member 52. The slight communication which still remains through vent passage 67 enables escape to atmosphere of any slight amount of air which may possibly leak past valve bead 82 from chamber 20.

As the pressure `within chamber 21 gradually increases, it exerts an increased upward `force against diaph-ragm 22, and through the diaphragm against valve 23. Ultimately, when the pressure in chamber 21 reaches a value great enough to overcome the pressure in chamber 20, valve 23 moves upwardly from its FIG. la position to its FIG. 7 position, in which position further upward movement is prevented by engagement of surfaces 60 and 84 on member 52 and the valve 23 respectively. In this condition, air may flow from chamber 20 radially inwardly past valve bead or ridge 82 of element 23, and then axially between surfaces 59 and 79 to flow radially outwardly through passages 85 in member 52 and into groove 49 for ilow from that groove through passage 90 to the controlled unit 15. Thus, after expiration of the desired time interval, air is admitted to unit 15, to actuate it. Since flange 78 of valve element 23 is larger than ange 77 of the valve element, the effective area of the valve element which is exposed to the pressure in chamber 21 is greater than the area exposed to the pressure in chamber 20, to thus assure ultimate attainment of adequate pressure in chamber 21 to open the valve and hold it open.

After valve element 23 has opened, the pressure Within chamber 20 decreases rather rapidly even though main control valve 14 may still be open. To assure this rapid drop in pressure, restriction 93 in the air passage leading into chamber 20 is preferably so designed that the restriction offered lby this passage to the inflow of air is greater than the restriction offered to air outflow through the various passages leading from chamber 20 to unit 15. That is, the relationship between these two restrictions is desirably such as to prevent air from flowing into chamber 20 as rapidly as it exhausts. Preferably, the restriction to inflow is sufficiently greater than the restriction to outow to prevent air inflow through passage 93 at a rate more than about 40 percent (for be'st results not over about 30 percent) of the rate of air outflow to unit 15. This assures a rapid and instantaneous actuation of valve 23 from fully closed to fully open position, so that actuating air is admitted to unit very suddenly rather than by slow seepage, and as a -result the timing of unit `15 is rendered very precise.

After the timed operation has been completed, valve 14 may be closed, to relieve the pressure in ball valve cham- 4ber 94, so that ball 97 may move away from its seat and allow discharge of the accumulated pressurized air from chamber 21 to the atmosphere at 100. This allows diaphragm 22 to move away from its contact at 64 with member` 52, to thus open communication between the timed unit 15 and the atmosphere through groove 62, and thereby relieve the pressure in the timed unit in preparation for the next successive operation. Also, this enables valve element 23 to be returned by spring 30 to its FIG. 1 initial position,

In order to adjust the length of delay interval for which the timer is set, an operator may turn either of the knobs 39 or `116. Knob 39 alters the time by' varying the effective size of chamber 21, while knob 116 changes the rate at which the metered air can flow into chamber 21. It is found that adjustment of metering valve 105 may function as a wide range adjustment, while actuation of knob 39 to change the chamber size may function as a very precise micro-adjustment, so that the timer may be set for any time within a wide range and yet be precise to a tolerance within one one-hundredth of a second at any point in that range. Even greater adjustment can be attained by removing metering valve parts 108 and/or 1111, and substituting other similar parts affording either increased or decreased restriction to fluid flow.

Because the air pressure acts against valve element 23 in both its opening and closing directions, it is found that the illustrated timer is relatively insensitive to changes in the pressure of compressed air supplied to the device. Whereas prior timers of which we are aware have required maintenance of the incoming air pressure at a very accurately regulated value, the present device will function with substantially no Change in the timing interval even though the supply pressure may vary several pounds per square inch.

Another way of adjusting the time interval is to connect into communication with chamber 21 an auxiliary chamber, as illustrated for example at 120 in FIG. 8, which chamber may be connected through a fitting 121 into the opening 103 in the side wall of the body part 17. In this way, connection of any of different sizes of closed chambers to chamber 21, in sealed relation, can in effect increase the size of chamber 21 and thereby increase the time interval required before attainment of adequate pressure in chamber 21 to actuate valve element 23.

We claim:

1. A timer comprising means forming first and second chambers for receiving pressure fluid, movable means to be actuated between first and second control positions and adapted to be initially held in said first position by pressure fluid in said first cham-ber and to subsequently be actuated to said second position by pressure fluid in said second chamber, means for restricting the flow of pressure fluid into said second chamber in a relation requiring elapse of a predetermined delay interval before the pressure in said second chamber reaches a value to overcome the pressure in said first chamber and actuate said movable means to said second position, said movable means including a valve unit having two axially spaced radially outwardly projecting flanges, and a structure about said valve unit having a flange projecting radially inwardly between said flanges of the valve unit and engageable annularly -with one of the flanges of the valve unit in a valving relation controlling the flow of fluid from said first chamber to an outlet passage, said outlet passage being formed in said flange of said structure and communicating with a space between said flanges of the valve unit.

2. A timer as recited in claim 1, in which said means forming said chambers include a body structure within which said valve element is movably received between the two chambers, said structure about the valve unit being essentially annular and being formed separately from and received within a circular portion of the body structure and being peripherally sealed annularly with respect thereto by two seal rings at opposite sides of said passage, said body structure containing a second passage communicating ywith said first mentioned passage and connectible to a unit to be controlled by the timer.

3. A timer as recited in claim 2, including a flexible diaphragm in the body structure between said second chamber and said valve unit for transmitting pressure therebetween.

4. A timer as recited in claim 3, in which said diaphragm has a peripheral portion operable upon an initial increase in pressure in said second chamber to close off communication from a space between said valve unit and said structure thereabout to a vent passage.

5. A timer as recited in claim 4, in which said chamber forming means include a wall of said second chamber which is adjustable within said body structure and operable upon adjustment to vary the effective size of said second chamber, there being a screw actuable from the outside of said body structure to adjustably shift said wall, said restricting means including an adjustable valve operable to adjust the restriction to flow of fluid into said second chamber, there being a common fluid inlet valve leading to said two chambers for admitting fluid past said adjustable valve into said second chamber and also for simultaneously admitting fluid with less restriction but with some restriction into said first chamber, there being a valve actuable by fluid from said inlet valve to close a vent outlet from said second chamber.

6. A timer comprising means forming first and second chambers for receiving pressure fluid, movable means to be actuated between first and second control positions and adapted to be initially held in said first position by pressure fluid in said first chamber and to subsequently be actuated to said second position by pressure fiuid in said second chamber, means for restricting the flow of pressure fluid into said second chamber in a relation requiring elapse of a predetermined delay interval before the pressure in said second chamber reaches a value to overcome the pressure in said first chamber and actuate said movable means to said second position, said movable means including valve means which in said first position close off the flow of fluid from said first chamber to an outlet passage, and which in said second position pass fluid from said first chamber to said passage, and a flexible diaphragm between said second chamber and said valve unit for transmitting force therebetween and having a portion operable upon the initial development of pressure in said second chamber to close off communication between a space downstream of said valve unit and a vent passage.

7. A timer as recited in claim 6, including means forming a smaller vent passage which is not closed by said diaphragm.

8. A timer comprising means forming rst and second cham-bers for receiving pressure fluid, movable means to be actuated between first and second control positions and adapted to be initially held in said first position by pressure fluid in said first chamber and to subsequently be actuated to said second position by pressure fluid in said second chamber, means for restricting the flow of pressure fluid into said second chamber in a relation requiring elapse of a predetermined delay interval before the pressure in said second chamber reaches a value to 9 10 overcome the pressure in said rst chamber and actuate FOREIGN PATENTS said movable means to said second position, and a valve 575 580 4/1958 Italy. operable upon initial admission of uid to said restricting means to close a vent outlet from said second chamber. WILLIAM F, ODEA, Primary Examiner.

References Cited 5 WILLIAM H. WRIGHT, Assistant Examiner,

UNITED STATES PATENTS .S. l. Cal'ltta U C X R 3,347,252 10/1967 Hanson 137-82 J 

